402 MILK 



are either thickly fluid or of jelly-like consistency, the firmness of 

 which varies with the customs of the different peoples in treating 

 the milk. The acidity is relatively high. 



The second organism is Streptococcus lacticus, whose function 

 is the initiating of the souring process. The third organism is a 

 saccharomyces, which produces aroma and a very slight, almost 

 negligible alcoholic fermentation, the high temperature of incuba- 

 tion restraining the growth of yeasts. By inoculating sweet boiled 

 milk with pure cultures of these three micro-organisms the proper 

 fermentation takes place and the product is normal. 



In addition, however, other micro-organisms are invariably 

 found in these fermented milks, and their presence has been the 

 cause of some confusion in scientific investigations inasmuch as 

 their functions have been sometimes misunderstood. As a mat- 

 ter of fact, these organisms are contaminations and sometimes 

 perhaps spore-forming bacteria that survive the boiling process. 

 Owing to Metchnikoff's propaganda, yoghurt, the fermented milk 

 of the Bulgarians, has been made very prominent. It does not, 

 however, differ materially from milk foods used by other nations, 

 except in the fact that it is made from milk evaporated to one- 

 half or one-third the original volume. The universal occurrence 

 of Jactobacilli, streptococci, and yeasts in milk has made it pos- 

 sible for different peoples to evolve fermented milks independently, 

 with the result that the products resemble each other in large 

 measure. 



The quality of the milk used for preparing fermented bever- 

 ages and foods of superior quality is considered of great impor- 

 tance by the natives, but it is not likely that the milk is responsible 

 for failures as much as bacterial contamination. 



Yoghurt, joghurt, yaoert, yahourt, jaurt, jugurt, and kisselo 

 me"lko are names for the fermented milks of the Bulgarians, Greeks, 

 Turks, and inhabitants of the Balkan Mountains. Yoghurt is 

 prepared from buffalo's, goat's, or cow's milk in the following man- 

 ner: Milk is boiled in clean earthenware vessels over a slow fire 

 until the volume is reduced by one-quarter, one-half, or even more. 

 It is then cooled to between 45 to 50 C. and a small amount of 

 a previous lot added. This ferment is called "maya," "podk- 

 wassa," or "zakvaska." The ferment is mixed with the milk 

 and the vessel containing the mixture wrapped in skins and cloths 

 to maintain a uniform temperature. After ten to twelve hours 

 the milk is ready for consumption. 



If the fermentation is not disturbed the product is of jelly-like 

 consistency, has a sweet taste and agreeable odor. The sweet- 

 ness is intense in proportion to the degree of inspissation, and 

 acidity is about 0.8 to 0.9 per cent. The cooked taste which is 



